title: Occurrence and correlates of fatigue in psoriatic arthritis.
abstract: OBJECTIVE
  To determine the relationship between fatigue and disease-related and psychosocial variables in psoriatic arthritis (PsA).
  
  
  METHODS
  499 patients attending the University of Toronto PsA Clinic were administered the modified fatigue severity scale (mFSS). At the time of mFSS administration, clinical and laboratory measures of disease activity and damage were recorded. Linear regression models were used to examine the cross-sectional relationship between disease-related and psychosocial variables and mFSS scores.
  
  
  RESULTS
  At least moderate fatigue occurred in 49.5% of patients and severe fatigue in 28.7%. Univariately the vast majority of variables were significantly associated with mFSS scores. The final multivariate model was composed of female sex, the medical outcome survey short form 36 (SF-36) pain and mental health scales, the number of fibromyalgia tender points, the health assessment questionnaire (HAQ) and "ever used" methotrexate, and explained 54.5% of the variation in mFSS scores. The SF-36 mental health scale played the largest role in the multivariate model, uniquely accounting for 6.6% of the variation in the fatigue severity scale. The disease-related factors significant at the univariate level did not achieve statistical significance in the context of HAQ and pain measures.
  
  
  CONCLUSIONS
  Fatigue is a common symptom in PsA, and is associated, in a multivariate model, with pain, female sex, physical functional disability, medication status and psychological distress. Fatigue appears to provide some information that does not overlap with the core set of outcome domains in PsA.
authors.affiliation: Department of Health Studies and Gerontology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Husted
authors.forename: B D
authors.initials: BD
authors.lastname: Tom
authors.forename: C T
authors.initials: CT
authors.lastname: Schentag
authors.forename: V T
authors.initials: VT
authors.lastname: Farewell
authors.forename: D D
authors.initials: DD
authors.lastname: Gladman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015535:Arthritis, Psoriatic / Q000150:complications* / Q000188:drug therapy / Q000523:psychology; D001294:Attitude to Health; D004812:Epidemiologic Methods; D005221:Fatigue / Q000209:etiology*; D005260:Female; D005356:Fibromyalgia / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012737:Sex Factors; D013315:Stress, Psychological / Q000150:complications; D055815:Young Adult